Schottky Diodes on ZnO Thin Films Grown by Plasma-Enhanced Atomic Layer Deposition

Enhancement of the properties of zinc oxide (ZnO)-based Schottky diodes has been explored using a combination of plasma-enhanced atomic layer deposition (PE-ALD) ZnO thin films and silver oxide Schottky contacts deposited by reactive radio-frequency sputtering. The electrical properties of the ZnO thin films were systematically tuned by varying the deposition temperature and oxygen plasma time during PE-ALD to optimize the performance of the diode. Low temperature (80 °C) coupled with relatively long oxygen plasma time (>30 s) PE-ALD is the key to produce ZnO films with net doping concentration lower than 10
¹⁷
cm
^-3
. Under the optimal deposition conditions identified, the diode shows an ideality factor of 1.33, an effective barrier height of 0.80 eV, and an ON/OFF ratio of 3.11 × 10
⁵
.